Xfdesktop crashes when renaming a file that does not exist. 

Tested also with Thunar so that file was deleted from Xfdesktop while rename
dialog was open in Thunar, Thunar did not crash but gave an error note to user
--> maybe some failsade code can be used from Thunar?

Reproducible: Always
Steps to Reproduce:
1. Rename a file shown in desktop so that rename dialog is shown, leave the
dialog open
2. Delete the file with file manager
3. Accept the rename dialog
4. Xfdesktop crashes